Relation between BI and Cycles lamp energy/emission values?
Cycles is a physically based renderer, whereas Blender internal is not (it is a rasterizer I think), the two are fundamentally different, and hence no real relationship can be established between them.

Lamps in Cycles physically accurate, emission node intensity is specified as power in Watts, according to the manual, the exception being the sun lamp, which uses a power per area notation instead, as in Watts/m2, as stated in the previous link.

Blender Internal Render lamps are specified as an energy value from 0.0 to 10.0, which has no immediate real world physical connection, as far as I know.

While it is probably possible to establish some sort of "visual correspondence" between two lamps using an equivalent scene as reference, it is probably hard to establish any sort of mathematically correct one.

From there lamp power will likely progress linearly for both cases, so changing one for X units will probably have a similar effect in both scenes, so it may be possible to establish some sort of directly proportional relationship between the two.

As Cegaton mentions, other than that film settings like exposure, and color management and post processing will also have a noticeable impact in scene lighting.